How to swim on dry land

Giant sand dunes of Sussusvlei (note a springbok antelope in the lower right corner) [Canon 7D, Canon EF 100-400mm]

Namibia is one of the driest places on the planet. It is home to the Namib Desert, the oldest perpetually dry place on Earth, which has endured arid conditions for at least the last 55 million years. Most places in the Namib receive less than 10 mm of rain per year, some even less, and not every year (by comparison, Boston, one of the driest places in Massachusetts, receives over 1,100 mm of precipitation every year.) Not surprisingly the Namib Desert is full of organisms superbly adapted to life in a world without water.

And yet, despite the lack of water, many animals found in its dunes exhibit adaptations similar to those found in aquatic organisms. The fine sands of the desert have remarkably liquid-like physical properties, forcing the development of various kinds of “swimming”, “surfing”, and “diving” behaviors.

Last year I briefly visited Sussusvlei in the Namib, a place famous for its enormous, bright red and orange dunes. There I found an animal that exemplifies many characteristics of desert “swimmers.” Splay-footed cricket (Comicus capensis) is a member of the family Schizodactylidae, a strange lineage of the Orthoptera, found only in a few places of southern Africa and southwestern Asia. Morphologically these insects have remained virtually unchanged sine the Early Cretaceous, over 100 million years ago.

Their common name is derived from the shape of their feet, each of which has four long “fingers” that greatly expand the foot’s surface area, turning them into “paddles” that allow the insect to  run and “swim” in the sand. So effective are these paddles that it took me almost 10 minutes to capture this tiny, 15 mm long animal, as it jumped and zipped through the sand. Splay-footed crickets are predators, actively chasing and devouring other small desert invertebrates, but otherwise little is known about their biology.

Splay-footed cricket (Comicus capensis) [Canon 7D, Canpn 100mm macro, Canon MT-24EX twin light]

Splay-footed cricket (note the shape of its feet) [Canon 7D, Canon 100mm macro, Canon MT-24EX twin light]

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